Overview of Sildenafil / Apomorphine HCl Troche

Dosage Strength

General Information

Sildenafil
Originally intended to treat pulmonary hypertension, angina, and other cardiovascular diseases, sildenafil citrate was unintentionally discovered to be useful in males suffering from erectile dysfunction (ED). Prior to the discovery of its therapeutic effects in the treatment of ED, this condition was thought to be an unavoidable component of aging in men or the result of underlying psychological problems. After being approved by the U.S. Food and Drug Administration in 1998 for the treatment of ED, sildenafil citrate’s popularity has skyrocketed over the last few decades, with health care providers generally recommending this medication as first-line therapy in the management of erectile dysfunction in men. Other aspects that contribute to its attraction and popularity include the fact that sildenafil citrate can be taken orally on demand and is generally well tolerated with little side effects. 1

Sildenafil citrate is a vasoactive medicine that belongs to the pharmacologic class of PDE-5 inhibitors; it is a competitive antagonist of this enzyme. PDE-5 is distributed throughout the human body, particularly in the corpus cavernosum within the penis, striated and smooth muscle, and platelets. However, PDE-5 is more prevalent in the penile corpus cavernosum, which explains why sildenafil citrate can function selectively in this area of the body. 2

Sildenafil citrate is often used orally. It can, however, be given intravenously or sublingually. Although its most common therapeutic application is for the treatment of erectile dysfunction, it is also used to treat pulmonary hypertension, infant pulmonary hypertension, Raynaud’s phenomenon refractory to other vasodilators, and to prevent pulmonary edema at high altitudes. Following oral administration, sildenafil citrate is rapidly absorbed, primarily in the small intestine, and is then carried through the bloodstream to its site of action. The hepatic isoenzymes cytochrome P450 3A4 and cytochrome P450 2C9 metabolize sildenafil citrate in the liver. Following hepatic metabolism, metabolites are primarily eliminated in the stool and, to a lesser extent, in the urine. 234

The Food and Medication Administration classifies sildenafil citrate as a pregnancy category B drug. Studies have found no definitive dangers to fetuses when sildenafil is given to pregnant women. There are currently no proven clinical indications for the use of sildenafil citrate in women. To yet, no studies have shown that sildenafil citrate has the same benefits in women as it does in men. Other trials, however, are still continuing, and the results may provide additional insight into the usability and benefits of sildenafil in women. 5

Apomorphine HCl
Apomorphine, a non-narcotic morphine derivative, is approved as a sublingual film for the treatment of acute, intermittent ‘off’ episodes associated with Parkinson’s disease, as well as as a subcutaneous injection for use in patients with advanced Parkinson’s disease. Apomorphine has also been used as a diagnostic test for dopaminergic responsiveness in Parkinson’s disease to identify whether or not a patient would respond to levodopa medication. Apomorphine has a rapid beginning of action, a strong effect on parkinsonian hypomobility (‘off’ episodes) that is ineffective with oral medicines, and a therapeutic efficacy comparable to levodopa. Apomorphine is coadministered with the antiemetic medication trimethobenzamide due to the high prevalence of nausea and vomiting. Because of reports of extreme hypotension and loss of consciousness when apomorphine was combined with ondansetron, the use of 5-HT3 antagonists with apomorphine is not recommended. Apomorphine, like other dopamine agonists, has been linked to abrupt sleep onset during daily activities and impulse control symptoms (e.g., intense urges to gamble or spend money, increased sexual urges). During apomorphine medication, practitioners should look for hypotension, orthostasis, new or worsened impulse control problems, and patient reports of unexpected sleep onset. 6 7